Reports from all three countries show a wide range of success (or failure depending on how you look at it).
In some studies, almost half the patients reported sciatica down the leg after lumbar disc surgery. As many as 70 percent report residual low back pain. Weakness and loss of function are also problems reported after lumbar disc surgery.
Low estimates place these figures around 22 percent for post-operative sciatica and 30 percent of continued low back pain. Researchers around the world are trying to find risk factors for a poor result. Doctors would like to be able to assess risk factors and predict who will have a good result.
For now there's no reason to go anywhere else for this operation. The results are the same on both sides of the continent and ocean.